After a brief statement in which he said he would offer his resignation to the Prime Minister, Lord Bates left the chamber, prompting dries of "no" from shocked peers.

“I offer my sincere apologies to Baroness Lister for my discourtesy for not being in my place to answer her question on a very important matter at the beginning of questions.” he said.

“During the five years of which it’s been my privilege to answer questions from this despatch box on behalf of the Government I have always believed that we rise to the highest possible standards of courtesy and respect in responding on behalf of the Government to the legitimate questions of the legislature.

“I am thoroughly ashamed at not being in my place and therefore I shall be offering my resignation to the Prime Minister."

Labour peer Baroness Smith said Lord Bates did not need to resign for the “minor discourtesy” and all that was needed was an apology.

His resignation is yet another blow for Theresa May, who is already reeling from mounting speculation that she should quit as Prime Minister.